A power semiconductor device is used to control the main power of a wide range of apparatuses and devices, from industrial equipment to home electrical appliances and information terminals, and particularly, a high reliability is required for a transportation unit for in-car use or the like. As a heretofore known power semiconductor device, PTL 1 proposes a power semiconductor device wherein a power semiconductor element is bonded via a solder to the upper surface of an insulating substrate, an aluminum heat dissipation member is bonded via a solder to the rear surface of the insulating substrate, and furthermore, an upper electrode of the power semiconductor element is connected to an external terminal via a bonding wire.
As in PTL 1, a reduction in thermal resistance in a bounding portion is achieved by using a solder to bond the heat dissipation member and the insulating substrate, and a lightweight power semiconductor device is obtained by using the aluminum heat dissipation member. In PTL 1, the portion of the heat dissipation member bonded to the insulating substrate is fitted in an iron frame material, thereby restraining the aluminum heat dissipation member from expanding due to heat.
Also, PTL 2 discloses a power semiconductor device using a metal sintered body to bond a rear surface electrode of a semiconductor element and a wiring member. In this heretofore known example, a paste-like bonding material is applied to the circuit surface side of the wiring member, and is pressurized and heated from upward and downward with the rear surface of the power semiconductor device disposed on and opposite the bonding material, thereby forming a bonding layer of the metal sintered body. As in PTL 2, the metal sintered body is used to bond the semiconductor element and the wiring member, and thereby no crack occurs in the bonding portion, improving a bonding reliability in high temperature operation.